Proximity ammeter



Feb. 23, 1954 c. 3. BATHGATE 2,670,458

PROXIMITY AMMETER Filed Feb. 3, 1950 FIG. 2

FIG. 1

7 i 2 as IN VEN TOR.

CARL 0. BA THGATE AWORM Patented Feb. 23, 1954 PROXDWITY AMMETER Carl 0. Bathgate, Rumson, N. J., assignor to Bendix Aviation Corporation, Teterboro, N. J a

corporation of Delaware Application February 3, 1950, Serial No. 142,265

3 Claims. 1

The present invention relates to electrical measuring instruments and more particularly to electrical measuring instruments of the proximity type.

Due to increased demands put on generating equipment required by greater current loads in mobile equipment, shunts have become an increasing problem in ammeter circuits. In most installations, it is a decided disadvantage to have the circuit dependent upon an ammeter or a shunt where the failure of the ammeter or shunt would disable the circuit. In order to overcome the above disadvantages, it is an object of the invention to provide an ammeter requiring no direct wire connections. 5

A further object of the invention is to provide an improved proximity ammeter.

A further object of this invention is to provide an improved current measuring device.

A further object of the invention is to provide an improved self-contained current measuring instrument for positioning adjacent to a conductor to give a direct reading" of current.

These and otherobjects and features of the invention will appear more full hereinafter from a consideration of the following description taken in connection with the accompanying drawing wherein two embodiments of the invention are illustrated by Way of example.

In the drawing:

Figure l is a sectionalside view of a meter embodying the invention.

. Figure 2 is a partial cutaway rear view of the meter of Figure 1.

Figure 3 is a front view of the meter of Fig- ,ure 1.

Figure 4 is a sectional side view showing a different embodiment of the invention.

Figure 5 is a partial cutaway rear view of the 'meter of Figure 1.

manner- A hanger 6 and a dial '1' are secured to the opposite end of the support members 5 by screws 8 or in any other suitable manner.

A movement unit 9 is supported between a bearing seat I0 in the bracket 6 and an adjust- U able bearing seat II in the dial I. A spindle I2 is rotatably mounted by the bearing seats I0 and II. The spindle I2 has a soft iron armature I3 mounted in a fixed position thereon. A pointer I4 is securely fixed to the spindle and extends through an opening I5 in the dial I which moves over a scale I6 on the dial 1. A soft iron zeroing armature I! is carried by the spindle I2 and is mounted for axial movement relative to the armature I3. A counterbalance I8 is mounted on the spindle to offset the weight of the pointer I4.

A permanent magnet I9 is secured to the hanger 6 adjacent to the movement unit 9 by r clips 20 or any other suitable manner.

Current carrying conductors 2| are held in fixed relation to the movement unit 9 by means of a bracket or clamp 22. The clamp 22 has a removable portion 23 secured to a fixed portion 24 by a screw 25. The clamp 22 is attached to the housing 2 by means of bolts 26 and nuts 21. A mounting bracket 28 is also held by the bolts 26 and nuts 21 and cooperates with a flange 29 on the housing 2 for securing the meter to an instrument panel (not shown).

Referring now to Figures 4 and 5 for another embodiment of the invention wherein like parts have been assigned the same reference numerals as in Figures 1, 2 and 3, there is shown an ammeter 3I having a non-magnetic housing 2 with a transparent window 3 forming the front thereof as previously described.

A pair of non-magnetic support members 5 are secured to the rear wall of the housing 2 in any suitable manner. A bracket member 32 is carried between the two support members 5-and is secured thereto. A permanent magnet 33 is pivotally mounted on each of the support members 5. Also carried by the support members 5 is a dial 1. The bracket member 32, magnets 33 and dial I are secured to the support members, 5 by screws 8.

A movement unit 34 has a spindle I2 rotatably supported by the bearing seat III in the bracket member 32 and the adjustable bearing seat II in the dial I. The spindle l2 carries a soft iron armature I3 attached for rotation therewith. A1- so, securely attached to the spindle I2, vis the pointer I4 and counterbalance I8.

The current carrying conductor 2| is held in fixed relation to the movement unit 34 by a clamp 36. The clamp 36 has a removable portion 37 secured to a fixed portion 38 by means of the screw 25. The portion 3'! has a plurality of slots 35 for selectively placing the conductor M in a predetermined position relative to the move ment unit 34. The fixed portion 38 has a serrated section 39 adapted to grip the conductor 2! in order to retain it in the selected position.

The invention operates upon the principle that a current passed through a conductor produces a field with its strength proportional to the current flowingtherinand its strengthvarying proportionately with th'e distance from the center of the conductor. Also that two or more conductors placed adjacent to each other produce a field strength that is proportionately stronger than for a single conductor. The increase in field strength is additive as the number or cenductors increase. Thus, it can be readily seen that the invention is not limited to any specific number of conductors but may be one or more-as desired.

In operation, the assembled unit is placed adjacent to a current-carrying conductor and the influence of the magnetic field of the conductor affects the armature 1-3 in a manner to cause it to tend to align itself with the magnetic flux lines of the conductor field. As the armature $3 "is secured to the spindle 12, the movement thereof isindicated by the pointer 14 and'ispropor tional to the field strength.

ordento calibrate the instrument and to p'rovide means for zeroing the pointer and to pr-event oscillations thereof, the smallpermanent magnet I9 is installed adjacent to the moving armature l3 *and in'such a position so as to be in the magnetic flux field of the conductor -21. The addition zeroing arrhature i? is adjusted in relation to the magnet 19 to bring the pointer to zero upon 'no'cu'rr'eiit flowing in the conductor. Once adjusted the armature '53 remains iixed. --'Io '-c'a1ibrate the instrument for full scale defiection fora -'predetermined value of curreirt, the armature i3fis adjustedrelative to the conducto'r *2 "to providethe' desired scaledeflection.

fIn the operation of thefeihbodiinerit of Figures 4 =a'nd5, the assembleduni-t is placedadjac'erit to the icondu'ctor 23. The Iiiagriet's 3 up a hermal-magnetic fiux'iieldiipon no current newing in the conductor *2! which affects the arinat'u're i3 to'causeit to'zer'o thepeinter M. When eiirr'erit is passed through the "conducter 2!, an unbalanced 'ne1e is then set [up between the pole pieces of the magnet's 33 to feause a -greater pull on orie -sid eflof-tl' e armaturelefdepending an the direction of'curreiit'fiow. I H In order to calibrate the'instrumenfsoas to lir'nit the amount of pointer-deflectionior' a given current, the magnets 33 *are spreadap'art. B y prep r'iyspaem themagnets 3?.3 relativeto each othenfany desired eaubmeeii may be obtained. In instruments of this type, it isfde's'irabie to have a mumpie mnge'm order tofobtain'affull "scale deflction foncurrents of different fvalues without recalibratingthe meter. As the strength of the "field produced by the currentpassing through the conductor varies proportionately with the distance from the center of thecon- "ductor, the clamps has a pluralityofslotsy-3 9,

one-of which maybe selectedfor positioning the conductor 2! to give thedesired' deflection. Movthe conductor 21 to another slot willgive a different deflection. For example, the'fir'st slot may be calibrated for amperes, the second for 30 amperes. Thuawhen the conductor'is in I ithefirst slot, the meter wouldhave a full scale deflection for 1-5 amperes, and when 'theconductor is inthe second slot, the meter would have a full; scaledeflectionforBO amperes. While only two slots'hav e been illustrated, it'is'iihder stood 'that'it is not limited to two but may-tease or more depending upon the requirements of the particular application. Also the clamps 22 and 36 are interchangeable and may be used on either embodiment. Thus, by merely changing the clamps, the instrument will cover a wide range of current values. 4 v

Although hfnlyitwo embodiments of the invention have been illustrated and described, various changes in the form and relative arrangement of the parts, which will now appear to those skilled the, art, may be made without departing from the scope of the invention.

What is" claimed l. e 'rical measuring instrument which i'sactuated 'hycurr'ent flowing in a conductor adjacent thereto, comprising a non-magnetic housing, a pair of supporting members secured thereto, a bracket member and a dial plate secured to said supporting members, a shaft rotatably supported by said dial plate and said bracket member, said shaft having an armature, a pointer, a Zeroing armature, and a counter-mal ance attached thereto and rotatable with eaid shaft, a stationary permanent magnet secu'i ed to said bracket member and so "positioned respect tosaidzeroing-arniatiire t'o efiect sai' in'g 'ar'mature s'o as to maintain said p0; a predetermined position in theabseiice o f 'cur rent flow-in a conductor adjacent thereto nc'njmagnetic means for "pdsitioiiin'gsaid iristi ent relative to a conductor in -'w'liich the current thereinis to be 'measured. V t MW 2. An electrical measuring 'ihetrument is actuated by currentflowing 'in aeonductor'a'djacent thereto, comprising a heir-magnetic housing, a pair ofsupporting inembersjsecuredthereto, a bracket 'member a'nda dial plate secured to said supporting, members, a shaft rotatably supported by said dial -pl ate anfd saidbracketfmemher, said shaft having "an "ariiiature, a pointer, a zeroing armature, and a counterbalance J'attached-thereto 'a'nd rotatable with said shaft, a stationary permanent mag et secu eu to fs'aid bracket member anuj-se-p sitiqnee with re pect to said zeroing armature to -effect said zeroing armature so as "to I maintain said pointer in a predetermined pension inthe'ab'sence of exit flow in a conductor adjacent "thereto noh agnetic means for positioning $2,1 1 instrument relative 'toaconduct'or in which the currentjtherein, is to be measured, andfiii'eaiis 'ra varym 'ths position or said first armature re auvefte fsaid conductor to calibrate the deflection of 's'aid pointer for'ap'redeterininedcurrent. a 3. Anelectrical measuring instrument whichi's actuated by c rrent flowing imapcsnuuetor adjacent thereto, comprising a rion-mai'gnetichoii'sing, a pair ofsupporting'meinberssecuredthereto, a bracket, member and a emrpn e'semrec "to said supporting membersia 's'hfaftrotatablyfsupported by said dial platefanclsai'd bracket thembeng'said shaft having an armature, aphiht'er, a zeroing armature, and a counterbalance at- 'tached "thereto and "rotatable "with said shaft,

predetermined posiuenm th'e .absencef'of our- .maglrieti'c'meansjforpositioning I relative to a "conductor in which the current 'rentj how are eqnuuetpfaajamm "thereto 'sfaidfinstrufnefit therein is to be 'r'neasiiredj'ah'd "nenmi ign tic "means for varyingthe Tpositionof-said conduetor fiatiiietb said firtarniatilfe to calibrate the deflection of said pointer for predetermined current values.

CARL 0. BATHGATE.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 606,369 Varley June 28, 1898 634,965 Thomson Oct. 17, 1899 10 1,580,768 Todd Apr. 13, 1926 1,663,768 Miller Mar. 27, 1928 1,735,919 Eshbaugh Nov. 19, 1929 1,912,800 Stanton June 6, 1933 Number 6 Name Date Hockley Aug. 22, 1933 Reich Oct. 10, 1933 Arey et a1 May 21, 1935 Arey Aug. 3, 1937 Arey Feb. 7, 1939 Warner Oct. 3, 1939 Rich Mar. 28, 1944 Grady Nov. 11, 1947 Brown Apr. 27, 1948 Hoare Oct. 11, 1949 Diehl Jan. 6, 1953 

